The processing of photographic color negative films and the making of prints on color negative paper is customarily carried out either at a processing laboratory or, latterly, in a minilab.
The industry standard processes use the color developing agent 4-N-ethyl-N-(2-hydroxyethyl) amino-3-methyl-aniline sulphate (CD4) as the sole color developing agent for the film and 4-N-ethyl-N-(2-methanesulphonamidoethyl)amino-o-toludine sesquisulphate (CD3) as the sole color developing agent for the paper.
French Patent No. 2 554 935A1 describes a method of shortening the paper development time by combining the developing agents CD3 and CD4 wherein the CD4 acts as a development accelerator.
A number of the components of photographic processing solutions are consumed during processing and it is conventional to add a replenisher to the solutions to maintain their performance. A common procedure is to add a fixed amount of replenisher solution to, say, a color developer solution per square meter of photographic material processed. Usually the replenisher is mixed into the bath and any excess solution overflows to waste.
Japanes Kokai No. 62-52549 describes a processing system that has facilities for processing two types of silver halide color photographic materials, each through its own processing solutions wherein one of the color developing solutions is replenished and this replenished solution is used as the replenisher for the other color developing solution. Only one system is specifically described and this comprises using a standard color paper developer based on CD3 and containing benzyl alcohol. This paper developer is replenished and the replenished paper developer is fed to the film color developer which is also based on CD3 and contains benzyl alcohol. The color paper being processed is based on silver chlorobromide emulsions.
This system is unsatisfactory for a number of reasons. First, the dyes produced in the color film will not have the same spectral absorptions as they would have had when processed in the standard CD4 film developer. Hence, general use of such a process would mean that all the negative films of all manufacturers would probably need to be reformulated--an almost unthinkably expensive task. Further, the use of benzyl alcohol in the film developer would lead to the formation of tar often associated with CD3 paper developers. Moreover the Kokai does not described any substantial advantages over and above the slight savings associated with the use and mixing of a single developer replenisher rather than two.